This invention is generally in the field of medical devices and treatment methods, and more particularly devices and methods for treating respiratory deficiencies with electrical stimulation.
A variety of medical disorders may prevent a patient from breathing normally in a spontaneous fashion and may require some external ventilation assistance. This disorder can last for a limited time, such as in anesthetized patients or in people after a serious surgery or as a result of a serious illness. In certain cases the need for ventilation assistance can last for a long time, such as in patients suffering from chronic illness including Spinal Cord Injury (SCI) or from Amyotrophic Lateral Sclerosis (ALS), or in Cheyne-Stokes respiration patients. A common acute ventilation assistance technique is performed by providing positive pressure mechanical ventilation via an intubation inserted to the patient trachea via the mouth, which works by increasing the pressure in the patient's airway and thus forcing additional air into the lungs. This technique, while being effective, suffers from several drawbacks and risks including ventilator-associated pneumonia, pneumothorax, airway injury, and alveolar damage among others. Prolonged use of mechanical ventilation may also cause the body to become dependent on the ventilation due to weakening of the diaphragm and the costal muscles, as well as cause barotrauma, posterior lob atelectasis, or impaired hemodynamics. Accordingly it is beneficial to wean the patient off, or to reduce the assistance level, of the ventilation machine as soon as possible. For patients requiring mechanical ventilation assistance for prolonged periods, a significant portion of that time (some studies have shown up to 40% of the time) is spent weaning the patient from the mechanical ventilation.
Two other techniques for assisting breathing that are available today include phrenic nerve stimulation and diaphragmatic pacing. Both methods use electrical stimulation to induce contraction of the diaphragm using an electrode and an external pacing control box. The two phrenic nerves, which control activation of the diaphragm, run through the thorax, along the left and right sides of the heart, and then to the diaphragm. Phrenic nerve stimulation is performed by electrically stimulating the phrenic nerve to control the patient's diaphragm, which may induce a respiratory cycle. Conventional techniques include surgically implanting a nerve cuff around the phrenic nerve (at the neck or chest level), and then delivering an electrical stimulus from an externally located controller through the cuff to the phrenic nerve. This procedure is quite invasive, requiring incisions when deploying the nerve cuffs. In addition, the direct placement of the nerve cuffs around the phrenic nerves may damage the phrenic nerve. Additionally, phrenic nerve stimulation is limited to patients having a functional phrenic nerve below the implantation level.
Another method for electrically stimulating the diaphragm is known as diaphragmatic pacing. Conventionally, diaphragmatic pacing is performed by laparoscopically implanting four electrodes directly on the diaphragm (two on each side), with electrical leads connected to a controller residing external to the body. Conventional diaphragmatic pacing procedures are also relatively invasive, requiring incisions during implantation, presenting risk during the implantation procedure and risk of chronic infection at the lead entrance site to the body.
Accordingly, there exists a need for a less invasive, safer, and simpler system and technique to provide reliable diaphragmatic pacing and phrenic nerve stimulation. It thus would be desirable to provide alternative systems, devices, and methods for positioning and fixing diaphragm stimulation electrodes proximate to desired stimulation sites, particularly for phrenic nerve stimulation and diaphragmatic pacing.